Disclosed in U.S. application Ser. No. 189,354, filed on Sept. 22, 1980 by Toda and Osaka now U.S. Pat. No. 4,339,682 issued July 13, 1983 is a rotative motor which converts electrical energy into mechanical energy without employing magnetic circuits by utilizing a pair of piezoelectric bimorph elements.
In any motor, it is desirable that all the input electric power be efficiently converted to mechanical output power without being consumed by various types of losses. In the piezoelectric bimorph motor, an electric oscillator is often used to drive the bimorph. Thus, if the motor is highly efficient the oscillator circuit current is reduced so that, if a battery is used, the battery life is lengthened.
Another requirement of a motor is to increase the output power without increasing the motor volume. To do so in the piezoelectric bimorph motor, many bimorph elements have to be closely packed, and it is desirable that all the elements effectively drive the rotor.